1-13 Mendelian Patterns of Inheritance Flashcards
What is a “rare genetic variant”
A rare genetic variant is a mutation with a frequency
What is the MOI for Tay Sachs?
Rare autosomal recessive
The presence in males of a single allele at X-linked loci is called what?
Hemizygosity
Single-Gene vs Multifactorial Inheritance
Single-gene inheritance includes cases where a genotype at a single locus is both necessary and sufficient for expression of the characteristic under normal conditions (e.g. cystic fibrosis, sickle cell disease, fragile X syndrome). Multifactorial inheritance includes cases where multiple genes and/or environmental factors are necessary for the expression of a characteristic (e.g. height, hip dysplasia).
Mendelian vs Non-Mendelian Inheritance
Mendelian inheritance is the means of inheritance by which each parent passes down one allele for a given trait to the offspring (e.g. eye color, X-linked diseases). Non-Mendelian inheritance is any other means of inheritance (e.g. mitochondrial diseases).
Mode of interitance pattens
Dominant (e.g. Huntington’s disease), recessive (e.g. sickle cell disease), and mitochondrial (e.g. mitochondrial myopathy).
autosomal vs x-linked
Autosomal traits are inherited on the autosomes (e.g. sickle cell disease) and X-linked traits are inherited on the X-chromosome (mostly recessive; e.g. color blindness).
Recessive vs Dominant
A recessive characteristic is achieved when two copies of some allele received are not sufficient to overcome a certain expression threshold. A dominant characteristic is achieved when at least one copy of an allele received is sufficient to overcome some expression threshold.
new germline mutation
– A new germline mutation is a heritable mutation that occurs in the germline of the parent that isn’t present in the parent’s somatic cells. Such parents are germline mosaics.
Chimerism vs Mosaicism
Chimerism is when an organism has two distinct cell lines that are derived from two different zygotes (e.g. blood and bone marrow transfusions). Mosaicism is when an organism has two distinct cell lines that are derived from the same zygote (e.g. leukemia).
Expressivity vs Penetrance
Expressivity is the extent to which a genetic defect is expressed (mild to severe). Penetrance is the all-or-none expression of a genetic disease.
genotype vs phenotype
Genotype is the description of the alleles an organism has for a certain trait. Phenotype is the description of the characteristics associated with a genotype
Allelic, Locus, and Clinical Heterogeneity
Allelic heterogeneity is when two or more different mutant alleles are found at the same locus. Locus heterogeneity is when multiple mutant alleles at different loci can produce the same phenotype. Clinical heterogeneity is the association of more than one phenotype with mutations at a single locus.
punnett square
Pictoral means of determining possible offspring between two organisms given their genotypes for a certain trait or set of traits.
